Epicycloidal train of friction mechanism



Oct. 11, 1949.

J. BOUCHER EPICYCLOIDAL TRAIN 0F FRICTION MECHANISM Filed July 18, 1946:fonc-vues Boucher \v\\\/ENTOR.

Patented Oct. 11, .1949

EPICYCLUIDLT'TRAIN OF FRICTION 'MECHANISM Jaequesouchenlaria France,assignorto Compagnie De Pont A Mousson,

Nancy, France lApplicationgJulyrl, 1946, .Serial No. ,684,478 In FranceMay .'10, 1943 .SectionLBublicLaw 690, `August 8, l194:6 Patent expiresMay 10,1963

(Cl. I4-4.798)

The invention refer-sto anzep'icycloidaltrainof friction mechanism alleto vfbe iutilised las reducer or increaser of vspeeds of the known type,comprising a central shaft, zdriving or driven, in frictionalfcontac'twith=planet frction'rollu ers, the whole :surrounded by a distortedring, made of special steel, forming a band, the inner diameter ofwhich'isl slightlysrnaller4 than the circumscribecl-.circle tangent,.-atthe outer surfacezof the friction-rollers. The distorted ring,:forming a band, ensures tightening of the pressure between therollers'and the centralshaftand thereby, the .friction required for`transmission .of 4the movement,` by .increasing .it .orrby.'.r.educing`;it,:ao cording as thesysternisforincreasing orl"forrred ucing speeds.

In such a device, calculation shows and experience confirms that theband working in alternate flexion, is the npart-develo1zvingthemostifatigue. Such is the case, for instance, when the device has to revolveat high speed and more particularly still, in a multiplier of acentrifugal compressor at a speed equal to or greater than 20,000 r. p.m. for example.

The object of the present invention is a band that can be distorted, thelife of which is considerably increased when compared to that of asimilar band, made in a single piece.

It is known that in an epicycloidal friction systern, in order to limitwear, it is necessary for the surfaces of the elements in contact(axles, friction-rollers, interior track of the distortable ring) topossess the greatest hardness possible. That indispensable hardness isrealised by subjecting the steel to a hardening process but by so doing,the resilience is considerably decreased, such resilience being theapproximate index of the fragility at the alternated flexions.

Furthermore, for an equal distorsion, the fatigue is proportional to thethickness of the ring.

Finally, the degree of treatment, aiming at obtaining more or lesshardness or resistance of the steel, has a small influence on thecoeiicient of flexibility from which depends the resulting effortapplied by the satellites on the central shaft.

The best ring obtainable therefore, must comply with the followingconditions which are contradictory:

. Great degree of hardness Great resilience Small thickness Greatstrength High Coefficient r flexibility The invention has for object acomposite band meeting those conditions, and'which is formed ofatleasttwo concentric rings, to wit: a thick outer'ring, of great resilience,and a thin inner ring with a great degree of hardness.

Calculation shows and experience confirms that afband made in suchmanner withfseveral thicknesses and of metals of lsuitable shades,treated infanfappropriate manner, possesses considerably greater lifethan a band executed with a single thickness.

.Other clfiaracteristics of --the invention -will be evident from thedescription `which follows. 'By referring to the drawing, showing asectional view of 1an epicycloidal train of mechanism according to ftheinvention, I indicates the central shaft whichfends ina seatingZ,forming a'sun device on whi'chlrestfplanet friction-rollers 3 carried'inrotationby adriving meansld, integral'with a shaft 5, coaxial with theshaft I. The friction-rollers 3 are provided with bevelled partscooperating with abutment rings 6 and 1.

According to the invention, the band or distortable ring, fitted betweenthe friction-rollers 3 and the casing 8 which forms an orbit device, ismade up of two coaxial rings 9 and I0.

The outer ring 9 is the thicker; it is intended to .back up the frictionring I0 and to give an important radial pressure between thefriction-rollers il and said ring I0 and the central shaft I, this beingnecessary so as to avoid slipping between those parts. The thickness iscalculated in consequence, taking into account the distorsion necessaryto obtain the maximum efficiency of the system. That element is made ofsuitable quality steel treated to a low degree of hardness so that themetal can possess the maximum resilience.

By way of an example, the ring 9 can be made of nickel-chrome-molybdenumsteel (C: 0.10; Cr: 1.45; Ni: 1.20; Mo: 0.25) treated at 825 andtempered at 500, that steel has a tensile strength of kg./mm.2 and aresilience of 14 kgm.

The inner ring I0, undergoing the same distorsion as the thick ring, hasa thickness reduced to the minimum permitted by the possibilities ofmanufacture; that element is fitted without any loose play, into thethick ring 9. It is intended to offer the hardest possible surface, soas to avoid wear. It is therefore treated accordingly. At that point ofhardness there is a minimum resilience but the fatigue is much less thanthat of the thick ring.

By way of an example, the ring I0 can be made of chrome-steel with thefollowing compositions: C: 1; Sl: 0.15 to 0.50; Mn: 0.25 to 0.50; Cr:1.5. The treatment consists of hardening at S25-850 and tempering at160. The mechanical characteristics obtained are as follows: tensilestrength: 226 lig/mm.2 Brinnel hardness (load 3000 kg.)=626, Rockwellcorrespondence with diamond cone loaded to 150 kg.=61.

For an interior diameter of 117 mm., the thickness of the ring 9 is forinstance, 9 mm. and that of the ring l is 2 mm.

In that manner, it is possible to obtain a band in which the hardness ofthe two rings has the same value.

Naturally, it is possible to build a band of more than two thicknesseswithout exceeding the limits of the present invention. For instance, itcan be made up of or 6 rings of same thickness.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is: Y K 1. A friction epicycloidal traincomprising in combination a central member provided with a continuouscylindrical Sun surface, a rst carrier member in coaxial alignment withsaid central member, .a second carrying member surrounding said centralmember and rst carrying member, one of vsaid three members being adrivingv member whereas another is driven and they third member isimmovable, several planet rollers carried by said rst carrier member andin friction contact with said cylindrical sun surface around which theyare placed, and two endless coaxial rings located in a coaxial recess ofthe second carrier member, the outer of said rings being the thicker andpossessing a great resilience, whereas the inner ring, which constitutesan orbit friction ring, ts exactly in said outer ring, and is as thin aspossible, possesses great hardness and has an inner continu- 40 C. 0.10'Cr 1.45 Ni 1.20 Mo 0.25

said ringbeing hardened at about 625 C. and tempered at about500 C.whereas the inner ring is made of chome-steel comprising substantially:

C 1.00 'Si 0.15 to 0.50 Mn 0.25 to 0.50 Cr 1.5

saidinne'r vring being-hardened at about S25-850 C. and tempered'atabout *160 C.

3. A friction ,epicycloidal train as claimed in claim 1, whereinthevouter ring is formed of several elementary concentric rings.

" JACQUES BOUCHER.

REFERENCES CITED The -following references are of record in the le ofthis patent: A

France ;Dec. 3, 1920-

